Peripheral Blood Allogeneic Stem Cell Mobilization: Can We Predict a Suboptimal Mobilization?

Allogeneic peripheral blood stem cells mobilization is now the basis of most stem cell transplants. In a very limited number of cases, mobilization is suboptimal leading to further collection procedures, to suboptimal cell doses infusion with delayed engraftment time, increased risks of transplant procedure and of related costs. To date we have no recognized and shared criteria for early estimating the probability of poor mobilization in healthy donors. We then analyzed allogeneic peripheral blood stem cell donations performed at the Fondazione Policlinico Universitario A.Gemelli IRCCS Hospital from January 2013 to December 2021 in order to identify premobilization factors associated with successful mobilization. The following data were collected: age, gender, weight, complete blood cell count at baseline, G-CSF dose, number of collection procedures, CD34+ cell count in peripheral blood on the first day of collection, CD34+ cell dose per kg body weight of recipient. Mobilization efficacy was defined according to the number of CD34+ cells in peripheral blood on day +5 of G-CSF administration. We classified donors as sub-optimal mobilizers or good mobilizers according to the achievement of the 50 CD34+ cell/µL threshold. We observed 30 suboptimal mobilizations in 158 allogeneic peripheral blood stem cell donations. Age and baseline white blood cell count were factors significantly associated with negative or positive impact on mobilization, respectively. We did not find significant differences in mobilization based on gender or G-CSF dose. Using cut-off values of 43 years and 5.5×109/L WBC count, we built a suboptimal mobilization score: donors who reach 2, 1 or 0 points have a 46%, 16% or 4% probability of suboptimal mobilization, respectively. Our model explains 26% of the variability of mobilization confirming that most of the mobilization magnitude depends on genetically determined factors; however, suboptimal mobilization score is a simple tool providing an early assessment of mobilization efficacy before G-CSF administration begins in order to support allogeneic stem cells selection, mobilization and collection. Through a systematic review, we looked for confirmation of our findings. According to the published articles, all the variables we included in our model are confirmed to be strongly related to the success of mobilization. We believe that score system approach could be applied in clinical practice to assess the risk of mobilization failure at baseline allowing for a priori intervention.

Impact of Pretransplant Salvage Therapies on Outcome of Hodgkin Lymphoma Patients Performing Allogeneic Transplant.

BACKGROUND: Allogeneic transplant is an effective salvage therapy in patients with Hodgkin lymphoma (HL) relapsed or refractory (R/R) to previous treatments. In recent years, immunotherapies (conjugated antibody and checkpoint inhibitors [CPI]) showed interesting results and were used as bridge therapies to allotransplant. AIM: The aim of this retrospective study in Lazio region was to evaluate the impact of these new therapies on outcome after allogeneic hematopoietic stem cell transplantation (allo-SCT) in comparison with standard chemotherapies used in the past. METHODS: We selected all consecutive patients with diagnosis of HL transplanted in four hematology transplant units, and we collected data obtained from patients' records concerning all the treatments before allo-SCT. RESULTS: A total of 56 patients were enrolled in this study. All patients underwent allo-SCT for R/R HL. Seventeen patients (30%) received chemotherapy prior to allo-SCT (group B); they were treated between 2008 and 2015; and 39 patients (70%) received brentuximab vedotin (BV), CPI, or both before allo-SCT as a bridge to transplant (group A); they were treated between 2012 and 2020. Twenty-five patients were treated with BV alone, 2 with CPI alone, and 12 first with BV and then with CPI. No patient received concomitant BV and CPI. At 5 years from allo-SCT, overall survival (OS) was 59% and progression-free survival (PFS) was 65%. No statistical differences in OS or PFS were observed between patients in groups A and B. Relapse was significantly associated with a lower survival. The only factor associated with a reduced risk of relapse was development of any grade acute graft versus host disease (GVHD) (p > 0.02). CONCLUSIONS: This regional real-world experience shows the changes that have taken place in the last 10 years in R/R HL using new drugs to render a patient eligible for allo-SCT. This strategy appears to guarantee an impressive disease control with an increased risk of complications, for example, aGVHD, that appear to nullify this advantage at least in part.

Multicolor flow cytometry on pericardial effusion for a prompt diagnosis and treatment of hematological malignancies with heart involvement.

Background: Malignancies represent 15-50% of total causes of pericardial effusions (PE). Routine analyses recommended to be performed on pericardial fluid include general chemistry, cytology, polymerase chain reaction, and microbiological cultures. Multicolor flow cytometry (FC) is a laboratory test that already proved to be useful in the detection of lymphoproliferative and metastatic malignancies in pleural and peritoneal effusions, but current guidelines do not mention its use on PE to reach a diagnosis. Methods: Our institutional protocol foresees to routinely perform a multicolor FC analysis on pericardial fluid samples obtained by pericardiocentesis, in addition to other guidelines-recommended analyses. A sample of 15-30 ml is analyzed using a lyse and wash staining method using combination panels of antibodies, allowing to detect specific cellular subpopulations, analyzing tens to hundreds of thousands of cells in few seconds. The present manuscript aims to report our single-center experience with this diagnostic tool in patients presenting with PE requiring pericardiocentesis. Results: Routine use of multicolor FC on pericardial fluid samples in our institution allowed to reach a definite diagnosis of cardiac lymphomas in two patients presenting with otherwise unexplained severe PE. This resulted in immediate start of combined immunotherapy, with patients' clinical improvement. At 6 months follow-up both patients are alive and presented a complete disease regression. Conclusion: Preliminary evidence from routine use of multicolor FC on PE support that this is a promising tool to reach a rapid diagnosis of hematological malignancies with heart involvement, leading to a prompt initiation of targeted therapies.

PD-L1 expression in peripheral blood granulocytes at diagnosis as prognostic factor in classical Hodgkin lymphoma.

Hodgkin lymphoma (HL) is a neoplastic disease in which the inflammatory microenvironment plays a pivotal role in the tumorigenesis. Neutrophilia is a typical finding in HL at diagnosis and, in particular, in association with lymphocytopenia, is a negative prognostic factor. As the immune checkpoint Programmed Death (PD)-L1/PD-1 has become an important therapeutic target, we were interested in the expression of PD-L1 in peripheral blood (PB) leukocytes using flow cytometry and RT-PCR in patients with HL and healthy controls. Granulocytes were the major PB cell fraction expressing PD-L1. PD-L1 expression on granulocytes was higher in patients with HL than in controls and correlated with lower T-cell numbers in PB. We analyzed for associations between PD-L1 expression in PB granulocytes at the time of diagnosis with patient characteristics and outcome in 126 patients with HL treated with standard chemotherapy adriamycin, bleomycin, vinblastine, and dacarbazine. Increased PD-L1 expression in PB associated with advanced disease, systemic symptoms, positive interim positron emission tomography, and inferior progression-free survival (PFS). PFS at 4 years was 81% (95% C.I., 71-87%) in patients with normal PD-L1 expression and 56% (95% C.I., 35-72%) in patients with higher-than-normal PD-L1 expression (p = 0.002). In conclusion, PD-L1 expression in PB could become a potentially actionable prognostic factor in HL.

Expression of PD-L1 in peripheral blood reflects disease burden and predicts interim PET result and prognosis in classical HL.